Over the years compressors and expanders of many and various types have been found to have many uses, including for heat transfer purposes, and compressors and expanders of various types and designs have been developed for use therein or therewith.
In more recent years, the use of scroll type compressors has become common. Such scroll type compressors typically employ two interleaving scrolls that often, but not exclusively, employ involute vane geometries to pump, compress, or pressurize the fluids, such as liquids or gases, with such liquids or gases typically being introduced into the scroll type device through an inlet or input port and discharged through a discharge port.
Often, one of the scrolls is held fixed while the other scroll orbits eccentrically, without rotating, to trap and pump or compress pockets of fluid between the scrolls, although other techniques for effecting suitable relative motion between the scrolls for such result can also be utilized, including co-rotating the scrolls, in synchronous motion.
Such scroll type devices generally tend to be compact and to operate more smoothly, quietly, and reliably than previous types of compressors.
Typically, such scroll compressors are designed and intended to operate during normal operation in one direction, herein generally referred to as the normal or forward direction, in order to function properly within the systems where they are employed. With some of such scroll compressors, some limited reverse operation, although generally considered undesirable, may be permitted or tolerated, such as to mitigate flooded operation of the compressor at start up, but the overall operation is as a compressor operating in a forward direction. When so operated, such devices effect compression of the fluids introduced thereinto. One common use of such scroll compressors has been in air conditioning systems, whether for heating or cooling.
Some other scroll type devices of a somewhat similar design, though with different connected porting, and with a differently configured involute or with a similar involute configured to eccentrically orbit differently than as a scroll compressor, have more recently been developed, with such devices intended, when properly configured and ported in a system, to serve an expansion function instead of a compression function. At least some of such scroll type devices typically employ scroll plates highly similar to the scroll plates of the previously referenced scroll compressors, with generally like interleaved involute wraps thereon, but such scroll type devices are designed to be normally operable in a direction that is the reverse direction from that of such previously referenced scroll compressors. Such scroll type devices are sometimes referred to as scroll expanders. One use of such scroll expanders has been for standby and Uninterruptible Power (UPS) applications wherein a compressed air battery uses air to drive a scroll expander which in turn drives a conventional generator to produce electricity.
In the past, such single stage scroll type devices, with their single pair of scroll plates, whether intended to effect a compression or an expansion function, have generally been designed or intended to be normally operable in only one direction within the systems in which they are employed, and to function during their normal operation as either a scroll compressor or a scroll expander, and not as both a scroll compressor and scroll expander.
In general, scroll type compressors have been limited to a single stage of compression due to the complexity and difficulties associated with two or more stages. However, some recent scroll type devices have been designed to include multiple stages, some with multiple pairs of interacting scroll plates, to achieve more desirable performance and results. Some more recent scroll type compressors, such as those disclosed in U.S. Pat. Nos. 6,050,792 and 6,439,864, include multiple stages, with appropriate associated fluid ports, within a single scroll type compressor. Such scroll type devices are not operable to effect both compression and expansion functions by the operation of a single pair of scroll plates in a normal direction, however, and some require multiple pairs of scroll plates to realize the multiple stages.
Another recent scroll type device of interest is the invention, by the inventor of the present invention, disclosed in U.S. patent application Ser. No. 13/066,261. That invention is a scroll type construction that employs a plurality of fixed and orbiting scrolls arranged to operate as a three stage vacuum pump wherein the first stage acts upon working fluid provided at an inlet as a compressor, the second stage acts upon working fluid from the first stage as an expander, and the third stage acts upon working fluid from the second stage as a compressor, all as the scroll type device operates in a normal forward direction. While such scroll type device effects both compression and expansion within the single, multi-stage unit, wherein the compression and expansion operations are part of a single, desired operation, with the output of one stage feeding the input of the succeeding stage, the overall effect of such unit's operation is that of a vacuum pump. Moreover, such multi-stage operations require multiple fixed and orbiting scrolls in order to affect the staged, linear expansion and compression functions realizable therewith; both compression and expansion functions are not realizable in any single stage of the unit from the use of a single pair of scroll plates.
Consequently, even though the construction of U.S. patent application Ser. No. 13/066,261 has been designed to incorporate within a single scroll type device both compression and expansion functions, such functions have formed constituent parts of an overall compression operation, and the compression and expansion functions have not been available for separate and/or independent use and, in any event, are not effected by the normal operation of a single pair of scroll plates in a forward direction. In order to realize the staged compression and expansion functions of such construction, multiple pairs of scroll plates are required to be configured in particular manners. Consequently, even with such construction, realization of both compression and expansion functions from a single pair of scroll plates in a single scroll type device has not been possible.
Against such backdrop, it has also been recognized for many years that many waste heat energy sources, such as solar, engine exhaust, geothermal, and other sources that employ processes where the waste heat is exhausted to the atmosphere, currently exist, and that it would be advantageous and desirable if the energy in such waste heat sources could be recovered for beneficial uses, including for air conditioning purposes. Effective realization of such an objective has remained problematic, however.
It has been recognized by the inventors of the invention hereinafter described that, in order to capture and advantageously make use of the waste heat of such previously noted energy sources, particularly for air conditioning purposes, an expander can be utilized in an Organic Rankine Cycle (ORC) to generate power, and that the power from the Organic Rankine Cycle expander can then be used to power a compressor for a traditional vapor compression cycle for air conditioning, either heating or cooling. It has been further observed, however, that it is inefficient and costly to have to utilize separate expanders and compressors for such purpose.
To address such desires and the shortcomings and limitations associated with having to employ separate expanders and compressors, a novel scroll type device including compressor and expander functions through the use of a single pair of scroll plates in a single unit has therefore been developed.